paypal Pro verification not correctly processed

we've implemented Paypal Pro, all works, except the form verification.

Scenario:
A customer inserts wrong credit card data,
hits the next button,
then goes to the Confirm order page
and after checking term / condition and hitting the Confirm Order button he gets the error (at this point the form seems to be verified).

Correctly it should be, that this error is displayed immediately after he hits the next button, before the Confirm order page will be displayed.